Aluminum Fly Ash Research Articles

Triethanolamine assisted ball milling activation of high alumina fly ash: Grinding kinetics, activation mechanism

Mechanical force can significantly enhance the physical and chemical activity of high-alumina fly ash (HAFA). Microparticle fly ash (MFA) was produced through mechanical ball milling of HAFA. The study concentrated on the particle size distribution of MFA after ball milling for 30–90 min and examined the impact of triethanolamine as a grinding aid. The particle size distribution (PSD), grinding kinetics, and mechanisms of microstructure evolution were analyzed. To verify the chemical activity of MFA, a high-alumina fly ash-based environmental material (EMFA) was synthesized. The results indicated that the particle proportion of 1–10 μm in MFA exceeded 50 %, and the RRB function was more suitable for describing the grinding kinetics of MFA. The mineral structure exhibited an increase in the content of amorphous substances, leading to the formation of amorphous active aluminum (Al). The microstructure of MFA displayed a combination of gel-like and fiber-like structures, including large smooth areas and fragment stacking. However, after 90 min of ball milling, a dense pore structure formed. The addition of triethanolamine accelerated the fragmentation of large particles and the formation of a secondary aggregate structure, with D50 remaining stable between 5.424 and 5.736 μm. The maximum compressive strength of EMFA reached 22.34 MPa, meeting the MU20 level of the Chinese standard "Solid Concrete Brick" (GB/T 21144-2023). This study provides crucial theoretical support for the modification, activation, and resource utilization of HAFA.

Sustainable Concrete Roof Tiles: Integrating Aluminium Foil, Fly Ash, Solar PV, and Management

This research investigates the use of municipal solid waste cremated fly ash as a viable substitute for natural sand in building methodologies, with a focus on sustainability. The waste material is used in the manufacturing of concrete roof tiles that are combined with solar PV systems, providing advantages in terms of both thermal comfort and improved energy efficiency. These tiles exhibit thermal insulation prowess by effectively preserving a 2-degree temperature differential and collecting heat from solar panels to enhance their energy-production efficiency. In order to enhance performance even further, aluminium foil is strategically placed on all four sides of the roof walls. The foil acts as a reflector, redirecting solar energy towards the tiles, which leads to a 5% boost in power generation. Particular alignments, such as positioning in an east-west or north-south direction, result in further enhancements in performance of 4% and 3%, respectively. This comprehensive approach not only confirms the use of waste materials for environmentally friendly construction but also emphasizes their crucial role in promoting energy-efficient building methods.

Geopolymer Materials from Fly Ash-A Sustainable Approach to Hazardous Waste Management.

This study explores the utilisation challenges of fly ash from municipal waste incineration, specifically focusing on ash from a dry desulphurisation plant (DDS), which is categorised as hazardous due to its high heavy metal content. The ash's low silicon and calcium contents restrict its standalone utility. Laboratory investigations initially revealed that geopolymers derived solely from fly ash after flue gas treatment (FGT), in combination with coal combustion fly ash, exhibited low compressive strength (below 0.6 MPa). However, the study demonstrated significant improvements by modifying the FGT ash through water leaching. This process enhanced its performance when mixed with high-silica and -aluminium fly ash, resulting in geopolymers achieving compressive strengths of up to 18 MPa. Comparable strength outcomes were observed when the modified ash was blended with commercial cement. Leachability tests conducted for heavy metals (HMs) such as copper, zinc, lead, cadmium, and nickel indicated that their concentrations fell below the regulatory limits for landfill disposal: 2, 4, 0.5, 0.04, and 0.4 mg/kg, respectively. These results underscore the effectiveness of water-washing FGT ash in conjunction with other materials for producing geopolymers, contributing to sustainable waste management practices.

An investigation of slurry erosion behaviour in plasma-sprayed carbon nanotube-reinforced fly ash/alumina coatings using experimental analysis and artificial neural computing for marine and offshore applications

This study investigates carbon nanotube (CNT)-reinforced alumina fly ash (FA) coatings, namely AF (unreinforced), 1CAF (with 1 wt% CNT), and 2CAF (with 2 wt% CNT), on marine-grade steel. Microstructural analysis shows 1CAF coatings denser by ∼15.32% due to CNT reinforcement, while 2CAF coatings display ∼9.68% increased porosity from CNT agglomeration. Raman spectroscopy confirms CNT retention. 1CAF coatings exhibit ∼14.66% higher microhardness, ∼15.96% higher adhesion strength, and ∼15.66% improved fracture toughness compared to AF coatings, attributed to pore sealing through CNT reinforcement. Enhanced erosion resistance (∼14.59%) in 1CAF coatings was observed due to improved mechanical properties and CNTs mitigating crack propagation. Validation through an artificial neural network (ANN) modeling and regression analysis supports 1CAF coatings’ promise for harsh marine environments, offering enhanced durability.

Solvothermal synthesis and adsorption performance of layered boehmite using aluminum chloride and high-alumina fly ash

High alumina fly ash (FAHAl) is a kind of bulk solid waste unique to China, whose availability of high-value aluminum and the threat to the environment make its high-value utilization urgent. In this work, the alumina containing leaching solution obtained from Na2CO3 roasting and HCl leaching of FAHAl was used as the mother liquor to prepare layered boehmite in situ. The preparation process with AlCl3 as the raw material was also compared. The formation process and mechanism of boehmite, the choice of solvent, along with the adsorption capability of Congo red were analyzed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller method and adsorption experiments. Results showed that during the preparation of layered boehmite, the precursor Al(OH)3 from the reaction of Al3+ and OH– is transformed into boehmite γ-AlOOH. The existence of ethanol is beneficial to regulate and promote the growth of boehmite crystal effectively. When water and ethanol is mixed with a volume ratio of 2:1 and used as the solvent, the maximum specific surface area of the boehmite is obtained of 135.7 m2·g–1, and 99.16% of Congo red can be absorbed after 10 min when AlCl3 is used as raw material. As purified leaching solution is used as the mother liquid, the crystallinity of boehmite decreases slightly when the pH value decreases from 12.5 to 11. When pH is 11, the removal efficiency of Congo red reaches a maximum of 72.25%. This process not only achieves the extraction of aluminum and high-value utilization of FAHAl, but also provided a thought to prepare layered boehmite with adsorption properties.

Significance of addition of carbon nanotubes and fly ash on the wear and frictional performance of aluminum metal matrix composites

AbstractIn order to improve the wear and frictional behavior of the aluminum metal matrix composites, carbon nanotube, and fly ash were added as reinforcements. Powder metallurgy technique was used to fabricate the hybrid metal matrix composites. Experimentations were carried out using pin on disc type wear test rig. The analyzed experimental results showed that, in comparison to the pure aluminum and mono reinforcement combination, the wear loss and coefficient of friction of hybrid metal matrix composites were greatly reduced. It was noted that compared to pure aluminum wear loss was decreased to 89.58%, 86.97%, 83.3% by adding 0.25, 0.5, 0.75 wt% carbon nanotube (CNT), respectively. By the addition of 4, 8 and 16 wt% FA to pure Al wear loss was decreased to 83.85%, 89.58%, and 78.12%, respectively. It was also noted that compared to Al/8 wt% FA mono reinforced composites, wear loss was decreased to 77%, 71.26%, and 53.22% with the addition of 0.25, 0.5, 0.75 wt% CNT, respectively. With the addition of 4, 8, 16 wt% FA, wear loss decreased to 81%, 88%, and 75% over Al/0.25 wt% CNT composites, respectively. The microstructural study of the worn‐out surfaces revealed low abrasive and adhesive wear by the presence of carbon nanotubes and fly ash in aluminum metal matrix. The reinforcing mechanisms of the wear and frictional properties were also discussed.

Fabrication of sustainable closed-cell aluminium foams using recycled fly ash and eggshell powder

Closed-cell aluminum foams are a novel materials which consists of unique properties such as good mechanical strength combining low mass and high stiffness, high energy and sound absorption, corrosion resistance, and recyclability. In spite of these potential properties, the usage of expensive constituents (stabilizing and foaming agents) and processing methods of making foams hinder its wide spread usage in industrial applications. This work involves the use of cost-effective constituents for processing aluminium foams by stir casting technique. The industrial waste fly ash (Class-F) is used as a source of stabilizing agent and for the first time the viability of waste chicken egg shell is used as a foaming agent to produce sustainable aluminium foams. Ex-situ characterization investigations are carried out on the manufactured foams in accordance with industry standards. It is evident that the produced foams have a fine cell structures with appreciable compressive strength and energy absorption characteristics. The experimental findings indicate that eggshell powder can be used as a cost-effective foaming agent for synthesizing aluminium foams and fly ash as foam stabilizing agent.

Optimizing abrasive wear loss of Aluminum/Fly Ash and Aluminum/Rice Husk Ash metal matrix composites using AHP-EDAS and AHP-COPRAS techniques for enhanced performance

Lightweight aluminum metal matrix composites (MMCs), Aluminum/Fly Ash and Aluminum/Rice Husk Ash were developed using the stir casting route for automotive applications. As a result of the above consideration, automotive parts such as brake rotor and connecting rod, etc. have been the subject of research in a variety of areas. Finding the right material for the design under consideration requires an effective approach to material selection. Multi-criteria decision-making (MCDM) processes are helpful when dealing with ambiguity in material selection. To rank aluminum-Fly Ash (FA) and Aluminum-Rice Husk Ash (RHA) composites, integrated MCDM methodologies such as Analytical Hierarchy Process (AHP)–Evaluation Based on Distance from Average Solution (EDAS) and AHP–Complex Proportional Assessment (COPRAS) are utilized. The weights for each criterion are determined using the AHP approach, and the EDAS and COPRAS techniques are then used to rank the items. Three different particle sizes (0–53, 54–74, and 75–105 µm) of the reinforcement have been chosen for the selection criteria. Density, hardness, ultimate tensile strength, and compressive strength, and specific wear rate, and coefficient of friction of the manufactured composites evaluated. A thorough examination of the MCDM methods found that Al-FA composites with particle sizes of 54–74 µm were the most effective.

Rare earth element recovery and aluminum-rich residue production from high alumina fly ash by alkali pre-desilication enhance the mechanochemical extraction process

Recycling rare earth elements (REEs) from coal fly ash by conventional acid leaching may generate large amounts of harmful waste acid, and the obtained acid residues have low utilization value. Accordingly, a green non-acid leaching approach for REE recovery and Al-rich residue production from high alumina fly ash (HAFA) was developed based on the alkali pre-desilication enhanced mechanochemical extraction process. REEs mainly existed in the chemically stable amorphous aluminosilicate glass phase of HAFA, which hindered the leaching of REEs. Thus, NaOH solution (150 g/L) was used to dissolve the glass phase and release REEs from the glass phase under a mild condition (80 °C, 2 h). The released REEs could be easily extracted by green EDTA during the mechanochemical extraction process. The extraction rates of La, Ce, Pr and Nd were about 82.03–88.71%, and valuable Al-rich residue (68.23% Al2O3 content and 2.51 Al/Si ratio) can be obtained when the mass ratio of the pre-desilication residue to EDTA, milling time, rotary speed, and liquid-solid ratio were 2:3, 2 h, 500 rpm, and 0.8, respectively. The used EDTA and REEs in the extracted solutions can be recycled by pH adjusting and organic solvent extraction. Thus, this study provides a new idea for green and high-value utilization of HAFA.

Preparation of mullite whiskers from high alumina fly ash and its reinforced porous structure

Porous has been formed in samples when mullite whiskers are prepared by firing compacts of high-aluminum fly ash and ammonium aluminum sulfate hydrate with a small amount of sodium dihydrogen phosphate and SiO2 at high temperature for 4 h. The effects of the particle size of fly ash, the firing temperature, and the content of sodium dihydrogen phosphate on the porous structure and the formation of whiskers are discussed. The results show that the smaller the particle size of fly ash, the more uniform porous in sample after fired, which is more conducive to the nucleation of mullite whiskers. Additionally, the amount of whiskers formation increased significantly with the firing temperature increasing, nonetheless, the pore size of porous reduced and the aspect ratio of whiskers gradually increased by reducing the content of sodium dihydrogen phosphate; owing to the reduction of glass melt in the matrix, the Al2O3/SiO2 ratio of the formed mullite whiskers gradually decreased. Thus, in order to obtain mullite whiskers self-reinforcement porous ceramics with the relatively low cost and no pollution to the environment, through the above preparation process, the addition amount of sodium dihydrogen phosphate and calcination temperature should be properly controlled.

Effect of MoO3 addition on fly ash based porous and high-strength mullite ceramics: In situ whisker growth and self-enhancement mechanism

In this paper, using only high alumina fly ash as raw material and MoO3 as additive agent, the high-strength porous mullite ceramics were achieved by in situ mullite whisker growth via a calcination method. The influence of MoO3 addition on pore structure and mechanical properties of as-prepared mullite ceramics was investigated. The mechanism of MoO3 promoting the formation of mullite whiskers and improving the strength of matrix was elucidated. The porous mullite ceramic reached its best performance with a high porosity of 49.4% and an improved compressive strength of 13.03 MPa with 10 wt% MoO3 addition calcinated at 1300 °C. Specifically, MoO3 facilitated the mullite whisks growth mainly by reducing melting point of amorphous SiO2/quartz and changing crystal structure of Al2O3. The larger aspect ratio of mullite grain at 1300 °C was easier to form an interlocking structure, which enhanced the strength of mullite ceramic while maintaining high porosity.

Addition of Fly Ash and Aluminum Slag as Cement Substitute Materials to Cellular Lightweight Concrete

Most of the construction buildings that are often found use concrete as the main building material. The development of technology makes more and more new types of modified concrete, one of which is lightweight concrete. Lightweight concrete that is often found is lightweight concrete CLC (Cellular Lightweight Concrete). The construction of non-structural elements of the building applies CLC lightweight concrete at a lower cost than standard concrete due to faster work, more temperature resistance, ease of handling, and lighter density. This study aims to find the optimum percentage and effect of using aluminum slag and fly ash as a partial replacement of cement in cellular lightweight concrete. The test object is printed in a molding size of 5x5x5 cm3. The use of aluminum slag is 0%, 1.5%, 3%, 4.5%, 6%, and 7.5%, while the use of fly ash is 15% of the cement weight. The tests carried out included volume weight, compressive strength, and water absorption at the age of 3, 7, 14, 21, and 28 days. The results of this study, it can be concluded that increasing the variation of aluminum slag with fly ash content remains at 15% in each variation as a cement substitution, the most significant variation is 1.5%. The optimum compressive strength test results at a variation of 1.5% of 4.1 MPa with the highest specific gravity of 752 gr/cm3, and water absorption of 66.67%, it all specimens at the age of 28 days.

A High-Efficiency Alkali Circulation Process for Alumina Extraction from High Alumina Fly Ash via Improved Hydro-Chemical Method

A High-Efficiency Alkali Circulation Process for Alumina Extraction from High Alumina Fly Ash via Improved Hydro-Chemical Method

Preparation of porous mullite ceramic supports from high alumina fly ash

Preparation of porous mullite ceramic supports from high alumina fly ash

Properties and mechanism of mullite whisker toughened ceramics

High-strength ceramics were prepared from high alumina fly ash (HAFA) and activated alumina as raw materials with magnesia as a sintering additive. The growth kinetics and influence mechanism of secondary mullite whiskers were investigated. Meanwhile, the effects of the Al2O3/SiO2 mass ratio (A/S) and the amount of magnesia on the content and morphology of mullite in the green body were investigated, so as to emphasize the effect of the liquid phase in the sintering process on the growth of secondary mullite whiskers. The results showed that the aspect ratio of secondary mullite whiskers increased significantly after adding activated alumina to increase the A/S ratio of raw materials. When 30 wt% activated alumina was added, the mullite content increased by 5.39%, and the whisker length increased from 1.36 μm to 4.18 μm. The addition of magnesia improved the liquid phase formed during the sintering process and the K value method was used to determine the sintering liquid phase content under various conditions. It was observed that increasing the magnesia level by 1 wt% could raise the liquid phase content by 5–7%. When the total liquid content of the system was 30–40%, the growth activation energy in the diameter direction of the whisker reduced significantly, promoting the growth of secondary mullite whiskers along the C axis. The morphology of mullite gradually developed from fibrous to long columnar crystal, making it combine more densely with the green body matrix. Furthermore, the staggered long columnar mullite crystal structure changes the fracture mode of ceramics from intergranular to transgranular fracture, which fully uses the high mechanical strength of mullite. As a result, the fracture energy and strength of ceramics are significantly improved.

Investigation of Mechanical and Tribological Properties of LM6-Fly Ash Metal Matrix Composite

Composite materials assume a significant part in auto, aviation, marine, and defense applications due to its unique properties. Aluminum alloys have certain advantages over other alloys. In this paper, the composite material comprised of Aluminum Alloy LM6 and fly ash (150 – 175 μm) has been picked as lattice and supporting materials individually. Magnesium is added to lessen the surface pressure and evade the dismissal of the particles from the melts. Liquid state processing through stir casting procedure was adopted for fabrication of mmc into necessary shape and size according to the ASTM principles by energetically mixing at consistent speed and time. The fly ash with various syntheses (2%, 4%, 6%) were added with LM6 combination. XRD and EDAX were used to examine the structural analysis of MMC, and optical microscopy and SEM were used to investigate the microstructure on MMC. Wear test was also carried out on MMC to ascertain the wear rate and cof of different MMCs. There is substantial improvement of mechanical properties like tensile strength, micro hardness, and density of the composite.

Influence of Different Addition Ratios of Fly Ash on Mechanical Properties of ADC10 Aluminum Matrix Composites

Aluminum-fly ash composites are formed by the chemical reaction between fly ash and the high-temperature aluminum-based alloy, which melts to form aluminum oxide as a reinforcing phase, which belongs to a composite of in situ synthetic reinforcing phases. Compared to aluminum-based alloys, composites have superior strength, rigidity, damping capacity, and wear resistance, but lower ductility and toughness. In this study, different fly ash addition ratios (0, 3, 6, 9, 12, and 15 wt%) were added to the ADC10-2Mg alloy melt via stir casting to form the aluminum-fly ash composite under the chemical reaction at 800 °C for 30 h. Subsequently, microstructure observation, density and porosity measurements, and hardness and tensile tests were conducted to analyze the influence of different fly ash weight percentages on the mechanical properties of aluminum-fly ash composites. According to the results, an aluminum-fly ash composite with good dispersibility of fly ash debris can be prepared by stir casting, and the fly ash particles gradually decomposed small debris as they reacted with the aluminum-based alloy at high temperatures during a long-term reaction process. The density of the aluminum–fly ash composite was reduced by adding fly ash, and its hardness and tensile strength were improved as well. However, the porosity increased with the amount of fly ash and the ductility was diminished. For the aluminum-fly ash composite with 6 wt% of fly ash, its density decreased by approximately 2%, the hardness and tensile strength increased by 7% and 49%, respectively, and the ductility decreased by 35%, as compared to those of the ADC10 alloy.

Experimental Study on Subgrade Material of Calcium Silicate Slag

Calcium silicate slag (CSS) is used as a secondary solid waste produced by aluminum extraction technology from high alumina fly ash, and its resource utilization has always been a key issue to be solved. In this study, CSS was used to replace a portion of fly ash (FA) to prepare a new inorganic binder stabilized material for road base. The unconfined compressive strength (UCS), phase composition, microstructure, durability and performance index of the base of the test section of the CSS pavement base material were studied. The results showed that with the increase in CSS content, the UCS of pavement base materials gradually increased. Under standard curing conditions, the UCS increased 6.90~17.24% after 7 days, and 7.90~28.95% after 28 days. The main reason was that as the hydration time increased from 7 d to 28 d, the hydration products C-A-S-H gel and C-S-H gel increased, the [SiO4] polymerization degree increased, the crystal type changed, and the structure denser, which supported the good development of mechanical strength of CSS pavement base material. In addition, the research has been successfully applied to a pilot test in Hohhot, China. The freeze–thaw resistance, water stability and UCS of the CSS pavement base material were tested to meet the requirements of Chinese road construction standards, indicating that the application of CSS in pavement base is feasible.

Development of Al – Fly ash Composites: A step towards sustainability

The use of mechanical waste in current assembling is a major jump towards supportable turn of events. Fly ash is an industry waste obtained from thermal power stations during burning of pounded coal. Fly debris based composites having prevalent characteristics in correlation with alloy metals and particularly the aluminium matrix composites have larger scope of acknowledgment in various regions to replace the use of iron and prepares and discovered applications in aviation and vehicle sector. The present work endeavours one such use and lessening the requirement for removal of fly debris which thus makes extensive harm the climate. This work manages the creation through fluid metallurgy course mix projecting of Al amalgam with 0–5-8% load of fly debris and micro structural investigation through optical microscopy, SEM, XRD and EDX testing of aluminium fly ash composite to recognize the fly debris particle. The XRD examination showed that the translucent period of the fly debris was a viable supported stage. Meanwhile, the optical and SEM micrographs of the composite examples demonstrated that fly debris could be responded or settled in the grid of the aluminium. The micro hardness examinations were additionally used to concentrate on the Al–fly debris composites.

Extraction of alumina from high-alumina fly ash by ammonium sulfate: roasting kinetics and mechanism.

The recycling of aluminum is commonly an important step to achieve the high value-added utilization of fly ash, which is a kind of solid waste generated from coal-fired power plants. In this study, high-alumina fly ash was efficiently activated by ammonium sulfate method and the alumina was efficiently extracted. The effects of roasting temperature, roasting time, and ammonium sulfate/high-alumina fly ash mass ratio on the leaching rate of alumina were fully analyzed, and the roasting kinetics and reaction mechanism in the roasting process were discussed. The experimental results showed that the leaching rate of alumina in the roasted material achieved 93.57% with the roasting temperature of 673 K, the roasting time of 60 min, and the mass ratio of ammonium sulfate to high-alumina fly ash of 6 : 1. The roasting kinetics showed that the reaction between high-alumina fly ash and ammonium sulfate was controlled by internal diffusion, the apparent activation energy was 37.40 kJ mol-1, which accorded with the reaction kinetic equation 1 - 2x/3 - (1 - x)2/3 = 2.9546 exp[-37 400/(RT)]t. The reaction mechanism showed that the aluminum and structural damage mullite in the high-alumina fly ash reacted with molten ammonium sulfate to form (NH4)3Al(SO4)3 and NH4Al(SO4)2. Finally, (NH4)3Al(SO4)3 was transformed into NH4Al(SO4)2 with the increase of temperature.